Method of fabricating blower wheels



Jam 35, 119% Filed July 12, .1946

c. L. SCHWARZ 2,496,179

METHOD OF FABRICATING BLOWER WHEELS 3 Sheets-Sheet l INVENTOR. 65,42,440 A. Sam/A22 jmnefifi 395% g, L SQHWARZ 'iwfifi yfi METHOD OF FABRICATING BLOWER WHEELS Filed July 12, 1946 3 Sheets-Shem; 2

INVENTOR. 1. 6544440 1 "c/ /mwz 625 L a 4 Fromm? y Jam EM, WSQ s. L. sczHwARz 9 3 METHOD OF FABRICATING BLOWER VW-IEELS Filed July 12, 1946 3 Sheets-Sheet 3 HVVENTDR. GEE/1L0 L Scum/A22 my $5M film ATTOE'A/EY Patented Jan. 31, 1950 METHOD OF FABRICATING BLOWER WHEELS Gerald L. Schwarz, Cleveland, Ohio, assignor to .giir Controls, Inc., Cleveland, Ohio, a corpora Application July 12, 1946, Serial N0. 683,089

4 Claims.

My invention relates to blowers and methods of fabricating impellers therefor.

An object of my invention is to provide an improved, less expensive blower wheel construction.

A further object is to provide an improved method of making blower wheels or impellers.

Still another object of the invention is to fabri cate blower Wheels from sheet metal stock by punching and assembling formed sheet metal pieces.

Other and further objects, features and advantages of the invention will become apparent as the description proceeds.

In carrying out my invention in accordance with a preferred form thereof, strips of sheet metal or long, narrow pieces of other sheet material are bent so as to have a curved cross-section suitable for blower vanes. A pair of strips of sheet metal is passed through a punch press to form rabbets or arcuate slots therein which are open along one edge of the strip. The vanes are then dropped into the slots, preferably with the rabbetted strips spaced from the ends of the vanes, whereupon the strips are bent within their planes so as to close the slots and secure the vanes by holding and embracing the portion of the vane passing through the strip. Preferably, the closing of the slots is performed by a suitable type of bending device so that the strip is curved to lie along the circumference of a circle and the strip length is made such that the ends meet and may be joined by welding or other fusion process to form complete circular blower wheels or impellers.

The end rings formed by the bent rabbetted strips are secured to radial or diagonal spokes carried by a hub or shaft mounted in a suitable housing such as in conventional, centrifugal type blowers.

A better understanding of the invention will be afforded by the following detailed description, considered in conjunction with the accompanying drawing, in which Fig. l is a perspective view of a completed blower with a portion thereof brokenaway, representing an embodiment of my invention;

Fig. 2 is a fragmentary view of a length of ringforming strip showing a vane holding rabbet or arcuate slot before it has been closed by bending the strip;

Fig. 3 is a view corresponding to Fig, 2, illustrating the length of strip after the slot has been closed by bending the strip and showing the cross section of the portion of a vane embraced within the strip;

Fig. 4 is a perspective view of one of the vanes consisting of a bent, narrow sheet of material such as metal;

Fig. 5 is a schematic view representing in perspective a punch press which may be employed for rabbetting the ring-forming strip;

' Fig. 6 is a longitudinal, medial, sectional view of a blower wheel constructed in accordance with my invention and fragmentarily representing a portion of the housing;-

Fig. 7 is a. schematic diagram of the ring-forming strip-bending machine; and

Fig. 8 is a. fragmentary end view of the bent strip showing the manner of joining the ends to form a ring.

Like reference characters are utilized throughout the drawing to designate like parts.

As illustrated in Fig. 1, blower wheels constructed in accordance with my invention are adapted to be used in centrifugal blowers. of the type having a housing U with air-inlet throats l2 at either end (only one of which is visible) concentric with a shaft I: for carrying a blower wheel l4 driven by an electric motor 15 through a drive-pulley I6 and a belt I! driving a second pulley l9 (shown in Fig. 6) secured to the wheel shaft l3. It is to be understood that the shaft I3 is supported in suitable bearings l8.

As shown in Fig. 6, the blower wheel itself comprises a plurality of vanes 2| secured in a plurality of rings, for example, a pair of rings 22 which are in turn supported upon the shaft I! by means of spokes 23, shown in perspective in Fig. l, as extending diagonally from the central portion of the shaft l3 to the rings 22 and carried by a. suitable hub. The hub is not shown, as the latter portion of the blower wheel is a conventional construction not constituting a part of my present invention. Preferably, the vane securing rings 22 are spaced from the ends of the: vanes 2! in order to avoid interference with the natural streamline flow of air entering the blower housing along the contours of the throats 24.

Although my invention is not limited thereto, to facilitate securement of the vanes within the rings 22 the vanes may be notched as illustrated in Fig. 4, showing one of the vanes 2| provided with four notches 25 arranged in pairs :at the positions where the vane is to be engaged by the securing ring 22. Preferably, the vanes iii are formed of flat sheet metal which has been pressed to the curved form illustrated.

In order to form the vane securing rings 22, a strip 26 of metal is passed through an indexing punch press 21 having a die plate .28 and a punch 29 of such shape as to cut out rabbets 8| illustrated also in Fig. 2. The rabbets 3| are in the form of open arcuate slots, as illustrated more clearly in Fig. 2, tapering from a maximum width at the portion 32 to a minimum width at the portion 33. In addition, the slot 3| is provided.

with a V-shapedpeak 34 to avoid buckling of metal when the slot 3| is closed. Preferably also, in order to assure securement 'of the vane within the slot Ii after it is closed, shoulder portions are provided in the open slot 8 I. The taper or difference in breadth of the slot at the portion 33 and I2 is so chosen as to produce the desired degree of curvature in the strip 26 when it is bent to form a ring of the requisite diameter for the blower housing ii.

It will be understood that the sides 38 and 31 of the slot 3| lie along arcs of very nearly the.

same radii, the difference in radius of parts 38 and 31 corresponding substantially to the thickness of the sheet forming the vane -2| to be secured within the slot 3| The oflset of the shoulder portion 35 is also approximately one-half of the intended thickness of the sheet forming the vane 2iin order "to form a cloven bridge 38 re- As illustrated in Fig.3, the dimensions of various portions of a slot ii are taining the vane 2|.

such that when the strip 26 is bent within its own plane, that is, in a direction parallel to the plane thereof to form a circle or lie along the circumference of a circle, represented by the ring i4.

I the slot'li will close upon the waist portion 38 in a head adapted to be moved toward the stops 44 by an hydraulic cylinder 45. Each vise 42 is provided with jaws, preferably also actuated bydraulically, for gripping the strips 26 while the dies 43 are bending them against the stops 44, which have a curved die-mating surface .41 conforming in radius to the intended inner radius of the rings 22 in the finished blower wheel. The arrangement is such that both strips 28 are gripped simultaneously as they are bent simultaneously to form the blower wheel. This'as- .sures that each strip 26 will be bent tothe form lying along the circumference of a circle which lies in the plane of the original straight strip 26. .The pressure controls for the hydraulic cylinder 45 are provided with interlocks to prevent actu=- ation until the vise-jaws 46 have gripped the strips 26 firmly. It will be understood that the vanes 2l are to be dropped in the slots 8| as the strip 28 travels along the. supporting rolls 4| before the strip-reaches the bending die 43. The strip 26 may be chosen of suillcient. length to form a eompletecircumference of the ring 22 or a fraction thereof. After sufllolent vanes have been 4 a form complementary to the inlet "throats 24 as illustrated in Fig. 6A. Each ring 22 has the inner portion warped or bent outward to provide a throat 5| flaring out toward the vanes 2|.

The throat ii is so curved to an edge 52 that a tangent to the curve at the edge 52 is parallel to the stream-lines of iiow of air drawn in through the inlet 24. In this manner a Venturi efiect is produced and a maximum amount of air is drawn along the ends of the vanes. The warping of the ability to the wheel i4.

In the case of conventional double inlet blowers with end rings and radial spokes located at each end the air bypasses approximately fifteen percent of the length of the blade next to each inlet, which means that about thirty percent of the blade length is inoperative due to the solid ring construction. End radial spokes furthermore tend to cut oil about ten percent of the air which would otherwise flow into the inlet In my construction providing a Venturi eifect substantially the entire length of blade is active in moving air. By locating the spokes at a distance from the inlet, at the rings 22 the axial air velocity and air flow to the center portion of the blade are reduced so as to allow the ends of the blades to move air.

' The venturi 5| therefore not only serves to pocket a portion of the air in the inlet end of the blade, thereby allowing the ends of the blade to do useful work, but also allows air passing on to the center portion of the blade to reach the blade section adjacent. to and touching the venturi; By thus using the spokes as diverting dampers and allowing the ends of the blades to be open, the full length of each blade is utilized. This decreases the internal air velocity to increase the eillciency.

The forming of the rings 22 may be accomplished by means of a press having suitable mating die plates, the inner die plate being separable bent into the strip 28 to form a complete blower wheel, the abutting strip ends 4. are joined to gether in some suitable manneras by riveting or preferably by some fusion process such as welding to form a permanent joint 48, asillustratedin Inthe case of relatively short blower wheels.

into collapsible parts to permit insertion within the vane assembly and to fit between vanes.

My invention is not limited to the form of slot 3| shown in Figs. 2 and 3. As illustrated in Figs.

2a and 3a, a slot 52 may be provided with a heel 54 mating a key 55. This gives a positive lock and will not spread open when the flare is turned on the edge 5|. Preferably the slot 53 is so shaped as to leave slight clearances 51 and It in the finished ring 22 to compensate for variations in blade thickness and allow the edges 20 and I1 to grip the blades 2| solidly.

While I have described my invention as em- 1. The method of fabricating a blower wheel which comprises the steps of forming a plurality of vanes, punching open arcuate slots in a pair of strips, placing said vanes in successive slots of said strips, each vane having a portion spaced from one end thereof in a slot of one strip and a portion spaced from the other end thereof in aslot of the other strip, bending said strips within the planes thereof to close said slots and secure said vanes simultaneously with curving 5 said strips along the circumference of a circle, and joining the ends of the strip to form vanesecuring rings.

2. In the fabrication of a blower wheel the steps of forming tapered open arcuate slots in a. strip, said slots being broader at the open end, placing long narrow sheets, each in one of said slots to form a vane, and bending the strip within its plane along a curve in the plane to close the slots and secure the vanes in position along such a curve.

3. In the fabrication of a blower wheel, the steps of slotting a strip along the edge thereof, with the slots tapering to less width away from the edge of the strip, engaging sheet material with slots in said strip to form vane means, and bending the strip within its plane to close the slots and secure the vane means, whereby the strip is curved to form a circular vane-securing me 4. The method of fabricating a blower wheel which comprises the steps of forminga plurality of vanes, punching open tapered arcuate slots in a pair of strips, said slots being broader at the open end, placing said vanes in successive slots of said strips, each vane having a portion spaced from one end thereof in a slot of one strip and a portion spaced from the other end thereof in a. slot of the other strip, bending said strips within the planes thereof to close said slots and secure said vanes simultaneously with curving said strips along the circumference of a circle, and joining the ends of the strip to form vanesecuring rings, the amount of taper of the slots in relation to the curvature of the rings being such that the slots are closed upon the vanes.

GERALD L. SCHWARZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 

